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The worldwide population growth and increasing urbanization of the past few decades have brought with it unplanned development of urban areas, affecting not only environmental quality but also increasing vulnerability during natural hazards and disrupting crisis management. Public open space, as a suitable spatial element, provides the necessary possibility for effective crisis management in cities. The metropolis of Tehran, the capital city of Iran, is located on a plain threatened by numerous faults. The population density in hazardous zones and the lack of potential to deal with earthquakes have increased the city's vulnerability. Therefore, because the organization of urban development for the efficient management of cities requires sufficient understanding of the needs and attention to the level of vulnerability, the seismic resistance of Tehran metropolis based on the earthquake risk has been investigated. In the earthquake risk assessment, population density as the number of risk elements, lack of enough public open space and urban fabric as vulnerability, and ground motion values expressed in the form of horizontal peak ground acceleration, have been considered as hazard components. Then, in the current study, to improve emergency services and the ease of crisis management, priority development of public open space has been determined based on international standards of the World Health Organization, the Public Health Bureau USA, the European Union, and the United Nations. The results showed reducing the seismic risk of regions 4, 8, 10, 14, and 17 in Tehran is priority. [ABSTRACT FROM AUTHOR]

A power plant is an essential structure that powers various sectors of the economy. It is vital to ensure the safety of such structures from natural hazards like earthquakes. The probabilistic seismic hazard analysis (PSHA) is the most advanced method of estimating earthquake hazards and risks. PSHA is the standard method for making site-specific, earthquake-resistant designs for important structures like a power plant. In the present study, the PSHA has been carried out for a power plant site in Chittagong using the latest available information on seismicity in the region. An updated earthquake catalog homogenized in uniform moment magnitude scale was prepared for the region. Seismicity analysis was carried out, and the seismicity parameters for the region were estimated from the frequency magnitude distribution plot. The peak ground acceleration (PGA) and the spectral acceleration at the bedrock for 10% and 2% probability of exceedance within 50 years were evaluated using different source models and attenuation relations in a logic tree framework. The site was characterized based on the soil investigation data from 31 boreholes, and amplification factors considering the local geology (SPT-N values) were obtained through ground response analysis. Subsequently, the surface level peak ground acceleration was estimated and depicted as hazard contour maps. The power plant site was observed to have a large spatial variation of seismic hazard at different locations. [ABSTRACT FROM AUTHOR]

Probabilistic Seismic Hazard Assessment (PSHA) was carried out for the administrative region of Attica (Greece). Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) values were calculated for return periods of 475 and 950 years for five sub-areas covering the entire region. PGA hazard curves and Uniform Hazard Spectra (UHS) in terms of spectral acceleration (Sa) values were generated for Athens, Methana, and the capitals of each island of Attica (Salamina, Aegina, Poros, Hydra, Spetses, Kythira, and Antikythira). Area sources were adopted from the Euro-Mediterranean Seismic Hazard Model 2013 (ESHM13) and its update, ESHM20, taking into account both crustal and slab tectonic environments. Ground Motion Prediction Equations (GMPEs) proposed for the Greek territory were ranked for PGA and PGV. Each GMPE was reconstructed as a weighted model, accounting for normal and non-normal focal mechanisms for each area source. PGA, PGV, and Sa values were computed using a logic tree, integrating the seismotectonic models as major branches and sub-logic trees, comprised of multiple ranked GMPEs for each area source, as minor branches. The results showed higher seismic hazard values in sub-areas near the Gulf of Corinth and the slab interface, which could indicate a need to revise the active building code in Attica. [ABSTRACT FROM AUTHOR]

Abstract—To obtain realistic and correct estimates of seismic effects in the Baikal Rift Zone (BRZ), a ground motion prediction equation has been developed based on the records of local earthquakes (magnitudes mb ~ 3.4–5.5, hypocentral distances R ~ 15–220 km) obtained by Ulan-Ude and Severomuisk seismic stations. At the first step, in our previous works, using stochastic simulation of the accelerograms of the recorded local earthquakes we estimated the regional parameters of radiation and propagation of seismic waves (stress drop in an earthquake source, quality function of the medium, geometrical spreading, wave attenuation at high frequencies, local site amplification, etc). These parameters were then used to generate a set of earthquake accelerograms over a wide range of magnitudes (Mw ~ 4.0–8.0) and distances (R ~ 1–200 km) on a rock site, and a ground motion prediction equation (GMPE) describing the dependence of peak ground accelerations (PGA) and peak ground velocities (PGV) on magnitude and distance are constructed. The obtained PGA estimates are compared with those estimated from GMPE recommended for BRZ by the international Global Earthquake Model (GEM) project. The scatter of the estimates obtained based on GEM GMPE indicates the relevance of developing the own GMPEs for Russian regions based on the records of local earthquakes. The GMPE derived in this work can be used for seismic hazard assessment in the BRZ eastern part and will be updated as new data are acquired. [ABSTRACT FROM AUTHOR]

The Gulf of Corinth (Central Greece) is one of the most rapidly extending rifts worldwide, with its western part being the most seismically active, hosting numerous strong (M ≥ 6.0) earthquakes that have caused significant damage. The main objective of this study was the evaluation of seismic hazard through a probabilistic and stochastic methodology. The implementation of three seismotectonic models in the form of area source zones via a logic tree framework revealed the expected level of peak ground acceleration and velocity for return periods of 475 and 950 years. Moreover, PGA values were obtained through the stochastic simulation of strong ground motion by adopting worst-case seismic scenarios of potential earthquake occurrences for known active faults in the area. Site-specific analysis of the most populated urban areas (Patras, Aigion, Nafpaktos) was performed by constructing uniform hazard spectra in terms of spectral acceleration. The relative contribution of each selected fault segment to the seismic hazard characterizing each site was evaluated through response spectra obtained for the adopted scenarios. Almost all parts of the study area were found to exceed the reference value proposed by the current Greek National Building Code; however, the three urban areas are covered by the Eurocode 8 regulations. [ABSTRACT FROM AUTHOR]

The Nilüfer district experienced the most recent urbanization among the central districts of Bursa in South Marmara region with the completion of rapid construction. Since 358 BCE, many destructive earthquakes were reported on the branches of the North Anatolian Fault (NAF) which caused extensive damage to buildings and loss of life near Bursa city. Besides some studies conducted to define the soil behavior in the vicinity of Bursa, a seismic hazard study in Nilüfer is still lacking. We, therefore, carried out a microzonation study including the following steps. First, an earthquake hazard analysis was conducted and the peak ground acceleration (PGA) values were determined for an expected earthquake. In the next step, MASW (Multi-Channel Analysis of Surface Wave) measurements conducted at 54 points in 28 neighbourhoods of Nilüfer district were evaluated. Soil mechanical parameters were determined at 11 boreholes to assess the liquefaction potential. It was found that almost half of the study area suffers from low damage considering only the vulnerability index (Kg) index, which depends on the site effect. Therefore, in addition to the Kg values, we created a microzonation map using the results of soil liquefaction, settlement, changes in groundwater level, and the average values of spectral acceleration. The study area is classified by four damage levels changing from low to high. Using only the Kg index could not quantify the potential damage level in the study area, thus we showed that the districts of Altınşehir, Hippodrome, Ürünlü and Alaaddinbey, Ertuğrul, 29 Ekim, 23 Nisan, Ahmetyesevi and Minareliçavuş were identified at potentially high-risk damage zones. The results of this study clearly showed that considering the Kg index, which depends only on the local site effect, may lead to inadequate damage values. • The district of Nilüfer in the Bursa City will have high damage from any future potential earthquake in the middle branch of the North Anatolian Fault • Site effect and liquefaction are important problems in the study area. • Kg index, which depends only on the local site effect, may lead to inadequate damage values. • Microzonation studies and the Kg index have to been evaluated together for an resilience city management in urban planning. [ABSTRACT FROM AUTHOR]

The tectonically active southwestern part of Turkey is dominated by the Aegean Extensional Province. The primary aim of this study is to evaluate the seismic hazard for the cities in SW Turkey using a probabilistic approach. As part of this research, a new earthquake database based on a unified moment magnitude scale was created, which contains shallow crustal earthquakes from 1000 to 2021. The catalog's foreshock and aftershock occurrences were excluded depending on the space–time windows, and a catalog completeness analysis was conducted. The uncertainty in magnitude determination was taken into account. The seismic sources were defined as homogeneous area source zones, taking into consideration the active fault zones. The activity rate and the Gutenberg–Richter b parameter as earthquake hazard parameters for each seismic source have been evaluated by the Kijko–Smit maximum likelihood estimation method. An "efficacy test," which uses the average log likelihood value (LLH), was performed to find the suitable ground motion prediction equations for SW Turkey. The maximum magnitude (Mmax) of each seismic source was calculated based on the regional rupture characteristics and the Kijko–Sellevoll methods. Seismic hazard maps for SW Turkey were developed for Peak ground acceleration (PGA), spectral acceleration with periods of 0.2 and 1 s and for bedrock with a hazard level of 10% probability of exceedance in 50 years by using Geographical Information System software. Based on this study, the PGA values on the bedrock in SW Turkey range from 0.253 to 0.572 g. As part of this research, seismic hazard curves and uniform hazard spectrums were created for the settlement areas of the cities in SW Turkey. In addition to this PSHA, PGA values at the settlement areas with events at probable future rupture locations were estimated for different site amplification classes. [ABSTRACT FROM AUTHOR]

This study's objective is to evaluate the seismic risk for Burdur City (SW Turkey) using a probabilistic methodology. Within the framework of the study, a new earthquake catalog for Burdur City and the surrounding area was created with a unified moment magnitude scale. The region's seismicity was assessed using the Gutenberg-Richter recurrence relationship. Software called R-CRISIS (v18) was used to calculate risks. Analyses were conducted using New Generation Attenuation models. With hazard levels of 2% and 10% probability of exceedance in 50 years, seismic hazard maps for the peak ground acceleration and bedrock were created. The study's findings indicate that peak ground acceleration values on bedrock vary between 0.70-0.75 g and 0.44-0.48 g, respectively, for hazards levels of 2% and 10% probability of exceedance in 50 years. [ABSTRACT FROM AUTHOR]

The Andes, located along South America's western side, is among the world's longest mountain ranges and is one of the most intense seismic activity areas caused by the Pacific Oceanic plate sliding under the South American continent, mainly when the range passes through Peru and Chile, covering an area of 3.37 million km2. The Himalayas mountain range is among the most seismically active regions in the world, mainly when the range passes through Nepal, China, India and Pakistan, due to the collision between the Indian and the Eurasian continental plates, covering an area of 1.09 million km2. Eastern Anatolia mountain range of Turkey covering an area of 0.15 million km2 is also one of the most seismically and tectonically active regions due to the frequent occurrence of earthquakes. These three areas and other few in the vicinity of high seismicity were considered for this paper based on in situ working experience for several dam spillways and large dams with heights up to 335 m. Of these 50% under operation, 25% under construction and 25% under final design stages. The earthquake safety of dams is an important topic in dam engineering and dam safety, and the seismic behavior of dams subjected to severe earthquakes and mainly their consequences downstream must be very well defined providing the adequate seismic factors not only from the engineering point of view but also thinking on damage risks, for a proper application. This paper evaluates the main concept of seismic hazard analysis and the PGA value defined for these dams in the Andean, Himalayas and Eastern Anatolia mountain ranges for the MDE, SEE and OBE earthquakes and their implications for the dynamic and static analysis. [ABSTRACT FROM AUTHOR]

This paper presents a probabilistic seismic hazard assessment (PSHA) for Guilan Province, an influential, highly populated and strategic district to the south of the Caspian Sea in northern Iran. In this study, the peak ground acceleration (PGA) and spectral acceleration (SA) over bedrock are estimated for the whole area of the province. NGA-West2 and the EMME project attenuation relationships are applied and combined using the logic tree method. Seismic hazard assessment is then carried out to establish the maps of seismic hazard distribution based on PGA values for two hazard levels as suggested by the Iranian seismic code of practice. Finally, deaggregation analysis is performed to determine the magnitude and distance pair that most prominently contributes to the seismic hazard for each district, which is of great importance for the region, as this has not been done before. Comparing the results with those suggested by the Iranian seismic code of practice and those obtained by previous studies, a general agreement seems to exist, although some violations are observed for some areas, especially in the southeastern part of the province, highlighting a need for revision of the Iranian seismic code of practice. [ABSTRACT FROM AUTHOR]

The aim of this study is to conduct a probabilistic seismic hazard analysis and spatial variation of seismic hazard at the surface level for Northeast of Algeria, covering 4°E–9°E, 33°N–38°N. The most recent peak ground acceleration (PGA) attenuation relationship, along with the updated seismic catalog and the best knowledge on the seismic activity in the study area have been used to estimate the seismic hazard and its uncertainty. Two types of seismic source models, linear sources and areal sources, were considered to model the seismic sources. Different sets of ground motion prediction equations were used for different tectonic provinces to characterize the attenuation properties. The hazard estimation at bedrock level was carried out using a probabilistic approach and the results obtained from various methodologies were combined into a logic tree framework. In this paper, we generate PGA maps with 10% probability of exceedance in 50 years, for a rock site condition. The seismic site characterization of Algeria was done using topographic slope map derived from Digital elevation model data. We estimate the seismic hazard from the seismicity catalog and not from faults with recurrence rates obtained from geologic data. The hazard estimation at surface level, is achieved through the use of appropriate site amplification factors corresponding to various site classes based on topographic gradient. Spatial variation of surface level PGA for return periods of 100, 475 years and 2000 years are presented as contour maps. The maps obtained in this study are based on the assumption that the process of earthquake occurrence is inherently Poissonian, so that the probabilistic ground motion is time-independent. [ABSTRACT FROM AUTHOR]

We would like to make some comments on the paper by Hamidatou et al. (2019). Initially, these comments are motivated to reveal that, previous results on probabilistic seismic hazard analyses, some of them computed and published by our research group, are wrongly quoted in the paper by these authors. In our opinion, some other points are worthy of debate, mainly, but not only, the used seismic source zone model, the used logic-tree, and also the comparison of estimated values of peak ground horizontal acceleration (PGA) with previous results. [ABSTRACT FROM AUTHOR]

We have kindly received the comments by Hamdache and Pelàez on our published paper (Hamidatou et al. 2019); This article will give us the opportunity to provide more explanation and clarifications on the methodology followed during our work. We find these comments and critiques helpful for our future works. However, most of them were generated from the misapprehension of the paper by the comment authors. These remarks were mainly based on (1) the misjudging of the seismic source zone model used in relation to the active faults in the study area, (2) suspecting that the probabilistic seismic hazard PGA values were wrongly quoted from their analyses in our work, and (3) the logic tree usage , for which we here provide further general clarifications. [ABSTRACT FROM AUTHOR]

In this paper seismic hazard for the sourthern slope of the Greater Caucasus (Azerbaijan) was assessed by using five major parameters: moment magnitude, simulated peak ground acceleration (PGA) from four target earthquakes, intensity scenario, amplification factor and b value. The deterministic scenario-based seismic hazard assessment method was applied by using the seismic catalogues compiled by the Republican Center of Seismological Survey at Azerbaijan National Academy of Sciences. Additionally this study presents hazard assessment analysis on 67 active faults tracing in the southern slope of the Greater Caucasus, considering the fault's location, size and length, and calculating the magnitude for those faults and lineaments estimated by empirical correlations. Our findings are: (1) maximum earthquake of Mw 8.0 is estimated for the western area zone and is used to generate one of the seismic scenarios of the region; (2) intensity distribution classifies the region into the highest hazard level with intensity value of 7 and over in the westward part and also in the eastward of the studied territory, in contrast to some areas in the southern part of the region which has the lowest level with intensity value of 6 and over; (3) the b value distribution shows that lower values are observed in the western part of the region (Zagatala, Sheki), in the Shamakhi area and on some areas of the northern part indicating higher stress in those areas; (4) PGA map from scenario earthquakes demonstrates that the very high PGAs are scattered in the west and east parts of the study area, while independently from the epicenter of the target earthquakes, the low and very low PGA is scattered in the central part of the study area. Such seismic hazard analysis with consideration of one of the main five parameters and target earthquake scenarios could help the region's sustainable development against earthquakes. [ABSTRACT FROM AUTHOR]

Bayesian probability theory is an appropriate and useful method to estimate parameters in seismic hazard analysis. The analysis in Bayesian approaches is based on a posterior belief, also their special ability is to take into account the uncertainty of parameters in probabilistic relations and a priori knowledge. In this study, we used the program for seismic hazard Bayesian estimate which was elaborated by Alexey Lyubushin. Our study is the next in the sequence of applications of this software to seismic hazard assessment in different regions of the world. In this study, Bayesian approach has been used to obtain estimated seismic parameters. In order to reach this aim, 30 different source regions in Zagros seismotectonic province have been considered. The main assumptions are Poissonian character of the seismic events flow and properties of the Gutenberg- Richter distribution law. The a posteriori probability distribution functions of Mmax (T) and the tail probabilities P(Mmax (T)>M), that will occur in future time intervals of 10, 20, 50, 100 and 475 years are illustrated for source regions. The map of peak ground acceleration (PGA) zonation by probability level of 90% (in g) in rock bed for average return period of 50, 100 and 475 years is presented. According to the results, the maximum acceleration is estimated for the cities of Kermanshah, Ilam, Khorram Abad and Bandar Abbas which are related to NWZ1, NWZ2, NWZ3, NWZ7, NWZ8, SZ3, SH1, PG1 and PG2 sources. Finally, the results of this study are compared with obtained results of non-source approach. [ABSTRACT FROM AUTHOR]

In this study, an effort has been made to perform seismic hazard analysis (SHA) for the state of Assam, considering earthquake catalog collected since 1761–2015 using PSHA and DSHA methods at bed rock level. Earthquake catalog declustered and seismicity parameters (a & b) of faults estimated. The SHA performed using newly proposed modified attenuation relation and compared. Results are presented in the form of seismic hazard curve and peak ground acceleration (PGA) for each 33 district headquarters. The PGA at the bed rock level with 2%, 5%, and 10% probability of exceedance in 50 years and 100 years estimated. [ABSTRACT FROM AUTHOR]

Tasikmalaya is one of the earthquake-prone cities in Indonesia as a result of collision of the Indo-Australian and the Eurasian plate. Earthquake mitigation efforts are needed to reduce the impact of future earthquakes. One of the mitigation efforts that can be proposed is a re-evaluation of the seismic hazard of the city. The main objective of this study was to re-evaluate seismic hazard expressed in Peak Ground Acceleration (PGA) and spectral acceleration at bedrock level based on a probabilistic approach, particularly in Tasikmalaya City. We first processed the earthquake data then adopted the new 22 seismogenic structures as the earthquake sources. Furthermore, we determined the characterization of each earthquake sources, selected, and adjusted the ground motion attenuation, and logic tree processed to manage the uncertainty of earthquake recurrence, magnitude distribution, and ground motion attenuation. Using Probabilistic Seismic Hazard Analysis (PSHA), PGA and spectral acceleration at bedrock level corresponding to 2% exceedance of 50 years' probability were calculated. The seismic hazards were quantified in terms of PGA and spectral acceleration at two fundamental periods of 0.2 and 1.0 s. The results showed that the subduction interface zones in southern Java and background seismicity significantly contributed to the seismic hazard in Tasikmalaya City. If compared with the 2010 Indonesian earthquake hazard maps, the results have relatively higher values in the three hazard maps which might due to the different characterization of earthquake sources, earthquake catalogs, and the GMPE to be used. [ABSTRACT FROM AUTHOR]

Uttarakhand Himalayas are highly sensitive to seismic hazard with possible occurrence of high-magnitude earthquakes. Fewer waveforms are available from previously recorded earthquakes, which are insufficient for carrying out seismic hazard studies. The recently installed strong motion instrumentation network (SMIN) in India, particularly, in Indian Himalayas is providing useful data. Using recorded data from SMIN, time-dependent peak ground acceleration and observed peak ground velocity shake maps are drawn for two earthquakes widely recorded by SMIN in Uttarakhand region of Indian Himalayan belt. Open-source Earthworm software with new algorithms is used for drawing these shake maps. The source mechanism is computed for April 4, 2011 earthquake using waveform inversion technique to relate it to the trend of shake maps. The computed focal mechanism shows one of the nodal planes in NW–SE, which are consistent with shake maps for the same earthquake. These time-dependent plotted shake maps provide useful information on the initial rupture, as well as the potential directivity of the rupture. [ABSTRACT FROM AUTHOR]

This study deals with attenuation relation for Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and spectral acceleration of Iran’s major seismic zones (the Central Iran and Zagros zones) considering ground amplification of site classes. The main development of attenuation relationship in terms of site classes has already been published by the authors. This study discusses site amplification in spectral acceleration compared to the seismic design codes of Iran (Standard 2800, 2014) and FEMA368 limits of amplification. Moreover, the relationships between the PGA or PGV and average shear wave velocity at 30-m depth (AVs30) are presented. This helps to predict appropriate PGA or PGV for each site corresponding to its AVs30. [ABSTRACT FROM AUTHOR]

Bayesian probability theory is an appropriate and useful method for estimating parameters in seismic hazard analysis. The analysis in Bayesian approaches is based on a posterior belief, also their special ability is to take into account the uncertainty of parameters in probabilistic relations and a priori knowledge. In this study, we benefited the Bayesian approach in order to estimate maximum values of peak ground acceleration (Amax) also quantiles of the relevant probabilistic distributions are figured out in a desired future interval time in Iran. The main assumptions are Poissonian character of the seismic events flow and properties of the Gutenberg-Richter distribution law. The map of maximum possible values of Amax and also map of 90% quantile of distribution of maximum values of Amax on a future interval time 100 years is presented. According to the results, the maximum value of the Amax is estimated for Bandar Abbas as 0.3g and the minimum one is attributed to Esfahan as 0.03g. Finally, the estimated values in Bayesian approach are compared with what was presented applying probabilistic seismic hazard (PSH) methods based on the conventional Cornel (1968) method. The distribution function of Amax for future time intervals of 100 and 475 years are calculated for confidence limit of probability level of 90%. [ABSTRACT FROM AUTHOR]

The site-specific earthquake ground motion parameters were presented for the southeastern part of Muscat governorate, including amplification factor at different periods and the values of PGA and spectral accelerations at the surface. The study starts with assessment of the seismic hazard at bedrock level using the probabilistic approach. This assessment was preformed considering an updated earthquake catalogue. The outputs of the probabilistic seismic hazard were uniform hazard spectra for return periods of 475,975 and 2475 years. Spectral matching technique was applied to define the compatible ground motion time series based on the outputs of the probabilistic approach and the deaggregation process. The representative's dynamic soil profiles were determined using the in-situ measurements of compressional and shear waves. The effects of soil deposits on the propagated ground motions time series was evaluated using the equivalent linear analysis in the frequency domain. The final results clarified that, the fundamental site period at the middle coastal parts of the area has the largest values (0.2–0.276 s). The maximum amplification factors found to be 2.76, 2.36, and 2.8 for the periods of PGA, 0.1 s, and 0.2 s, respectively. The values of PGA and spectral accelerations at the surface level are also provided. [ABSTRACT FROM AUTHOR]

The region of Blida is characterized by a relatively high seismic activity, pointed especially during the past two centuries. Indeed, it experienced a significant number of destructive earthquakes such as the earthquakes of March 2, 1825 and January 2, 1867, with intensity of X and IX, respectively. This study aims to investigate potential seismic hazard in Blida city and its surrounding regions. For this purpose, a typical seismic catalog was compiled using historical macroseismic events that occurred over a period of a few hundred years, and the recent instrumental seismicity dating back to 1900. The parametric-historic procedure introduced by Kijko and Graham (1998, 1999) was applied to assess seismic hazard in the study region. It is adapted to deal with incomplete catalogs and does not use any subjective delineation of active seismic zones. Because of the lack of recorded strong motion data, three ground prediction models have been considered, as they seem the most adapted to the seismicity of the study region. Results are presented as peak ground acceleration (PGA) seismic hazard maps, showing expected peak accelerations with 10% probability of exceedance in 50-year period. As the most significant result, hot spot regions with high PGA values are mapped. For example, a PGA of 0.44 g has been found in a small geographical area centered on Blida city. [ABSTRACT FROM AUTHOR]

We study local site effects with detailed geotechnical and geophysical site characterization to evaluate the site-specific seismic hazard for the seismic microzonation of the Chennai city in South India. A Maximum Credible Earthquake (MCE) of magnitude 6.0 is considered based on the available seismotectonic and geological information of the study area. We synthesized strong ground motion records for this target event using stochastic finite-fault technique, based on a dynamic corner frequency approach, at different sites in the city, with the model parameters for the source, site, and path (attenuation) most appropriately selected for this region. We tested the influence of several model parameters on the characteristics of ground motion through simulations and found that stress drop largely influences both the amplitude and frequency of ground motion. To minimize its influence, we estimated stress drop after finite bandwidth correction, as expected from an M6 earthquake in Indian peninsula shield for accurately predicting the level of ground motion. Estimates of shear wave velocity averaged over the top 30 m of soil (VS30) are obtained from multichannel analysis of surface wave (MASW) at 210 sites at depths of 30 to 60 m below the ground surface. Using these VS30 values, along with the available geotechnical information and synthetic ground motion database obtained, equivalent linear one-dimensional site response analysis that approximates the nonlinear soil behavior within the linear analysis framework was performed using the computer program SHAKE2000. Fundamental natural frequency, Peak Ground Acceleration (PGA) at surface and rock levels, response spectrum at surface level for different damping coefficients, and amplification factors are presented at different sites of the city. Liquefaction study was done based on the VS30 and PGA values obtained. The major findings suggest show that the northeast part of the city is characterized by (i) low VS30 values (< 200 m/s) associated with alluvial deposits, (ii) relatively high PGA value, at the surface, of about 0.24 g, and (iii) factor of safety and liquefaction below unity at three sites (no. 12, no. 37, and no. 70). Thus, this part of the city is expected to experience damage for the expected M6 target event. [ABSTRACT FROM AUTHOR]

In depth assessment of seismicity distribution for a particular region like Fukushima, prefecture is key towards reliable seismic hazard analysis for the area. Assessment of seismicity becomes more challenging for those areas lying close to mega subduction zone like in this study. Development of accurate input data like seismicity and faults data can reduce bias in the results and can improve quality of analysis. To assess the influence of seismicity on hazard analysis, two approaches known as Gutenberg-Richter law and the Gumbel’s extreme asymptotic distributions are employed. It is found that b value calculated through Gutenberg-Richter law has shown better b value of 1.0 according to tectonics of the Fukushima area. However, Gumbel’s approach which uses maximum earthquake of each years have shown b value of 0.6 and used for calculating future earthquake potential. Comparison of earthquake distribution in both cases has shown that in areas where we have rich seismicity data Gutenberg-Richter law is found much applicable as compared to Gumbel’s approach. Fault kinematics is done through software called FaultKin6 developed by (Rick Allmendinger) which resulted that Idosawa fault is a normal fault based on the fact that P axis is greater than 45° showing extension in N-S direction for Idosawa fault. Resultantly, it is tried to highlight the need to take normal faults in seismic hazard analysis probabilistically in design when they exist within stress field of big subduction zone. Peak ground acceleration is calculated by using PEER NGA West-2 models for Idosawa fault, and 0.22 g is found as PGA value. [ABSTRACT FROM AUTHOR]

Kanpur City and Allahabad City are the most populous city and the largest urban agglomeration among other north Indian cities. Both the cities are situated along Ganga and Yamuna River. The study areas are one of the growing urban centers in Northern India. Two large Himalayan earthquakes experienced by this area during 1803 A.D. and 1934, and large-scale liquefaction was reported in and around the area along with the recent 2015 Gorkha earthquake which caused severe shaking. As per the IS-1893–2002, the study area lies in seismic zone III and the soils from the above cities are prone to liquefaction. However, no such attempt has been made so far for the detailed liquefaction potential map for the study area. The present study is an approach towards evaluation and preparation of spatial distribution map of liquefaction potential for the Kanpur City and Allahabad City using several bore hole data collected from the study area. The PGA used for the liquefaction potential analysis was taken from the ground response analysis of Kanpur soil and Allahabad soil. The PGA values are 0.25 and 0.18 g for Kanpur soil and Allahabad soil respectively. The results are presented in the form of factor of safety contour map at a depth of 7, 15, 24 and 30 m below the ground surface. The map indicates that most of the sites in Kanpur City and Allahabad City area are susceptible to liquefaction and hence this aspect has to be considered in earthquake-resistant design of foundations/structures in Kanpur City and Allahabad City. [ABSTRACT FROM AUTHOR]

Earthquake response analysis has been carried out for various locations in the State of Haryana (India) adopting the equivalent linear approach. For this purpose, geotechnical data have been collected from different government and private organizations. Based on the provisions of National Earthquake Hazards Reduction Program (NEHRP), all the sites have been classified using average N-value (N 30 ) for the soil profile. The shear modulus (G max ) values of the layers in a soil profile have been estimated using standard correlations. Cyclic Response has been accounted for using the standard shear modulus degradation and damping curves. Time histories from Himalayan Thrust System have been used as an input and soil amplification has been estimated at the surface using DEEPSOIL software. The results of the study have been formulated in terms of soil amplification map, response spectra, PGA along the depth, surface time histories and strain along the depth. These results can be used for dynamic analyses and design of structures, planning of advanced dynamic lab test etc. Moreover, it has been observed that sites in Haryana can significantly amplify ground motions and hence a site-specific design approach must be adopted for important structures. [ABSTRACT FROM AUTHOR]

Maximum magnitude (MM) earthquake in the Kopili fault zone of North-East India has been assessed using different approaches, which are primarily dependent on various parameters such as fault geometry, slip rate, geodetic moment rate, and convergence rate. The analyses reveal that the source zone has accumulated strain energy, during the last 72 years since 1943, enough to produce a strong earthquake of magnitude ≥ 7. On supplementing with the historical data, we conclude M w 7.3 as the maximum potential earthquake for the Kopili source zone. Such large earthquake, on its occurrence, may cause widespread significant ground shakings and damage to infrastructures in the study region. We, therefore, also simulated strong ground motion, in the form of peak ground acceleration (PGA), for the M w 7.3 potential earthquake using Empirical Green’s Function (EGF) approach for ten different sites. In the analysis, an earthquake of magnitude M w 6.5, which has been simulated using a recorded M w 5.3 earthquake, is used as Green’s Function. The two-step approach is adopted in the simulation process, as the required criteria, i.e., moment ratio of < 1000 between the target potential event (M w 7.3) and the element event (M w 5.3) could not be met. We found that the cities like Tezpur, Masamari, Tumuki, Dhekiajuli, Nagaon, Bomdila, Udalguri, Seppa, Hajoi, Behali, Guwahati, and Itanagar that are located ∼ 60–130 km from the source zone may experience very strong to moderate ground shaking with PGA ranging between 0.36–0.14 g. However, the cities located in the distance range of ∼ 130 – 300 km from the source, namely Jorhat, Ziro, Mokokchung, Dhubri, and Kokrajhar are expected to have low ground shaking with PGA < 0.14 g. The study therefore provides valuable insights to the likely seismic hazard scenario in north-east India. [ABSTRACT FROM AUTHOR]

We deliver a next-generation Probabilistic Seismic Hazard model of West Bengal based on improved seismogenic source characterization considering both the Layered Polygonal sources & Tectonic sources in the hypocentral depth range of 0–25 km & 25–70 km, seismic local-specific site condition, and adaption of appropriate region specific ground motion prediction equations in a logic tree framework. The surface consistent Probabilistic seismic hazard distribution in terms of Peak Ground Acceleration (PGA) & 5% damped Pseudo Spectral Acceleration (PSA) at different time periods for 10% probability of exceedance in 50 years have been generated and the design response spectra computed. [ABSTRACT FROM PUBLISHER]

Southwest Turkey, along Mediterranean coast, is prone to large earthquakes resulting from subduction of the African plate under the Eurasian plate and shallow crustal faults. Maximum observed magnitude of subduction earthquakes is Mw = 6.5 whereas that of crustal earthquakes is Mw = 6.6. Crustal earthquakes are sourced from faults which are related with Isparta Angle and Cyprus Arc tectonic structures. The primary goal of this study is to assess seismic hazard for Antalya area (SW Turkey) using a probabilistic approach. A new earthquake catalog for Antalya area, with unified moment magnitude scale, was prepared in the scope of the study. Seismicity of the area has been evaluated by the Gutenberg-Richter recurrence relationship. For hazard computation, CRISIS2007 software was used following the standard Cornell-McGuire methodology. Attenuation model developed by Youngs et al. Seismol Res Lett 68(1):58-73, (1997) was used for deep subduction earthquakes and Chiou and Youngs Earthq Spectra 24(1):173-215, (2008) model was used for shallow crustal earthquakes. A seismic hazard map was developed for peak ground acceleration and for rock ground with a hazard level of a 10% probability of exceedance in 50 years. Results of the study show that peak ground acceleration values on bedrock change between 0.215 and 0.23 g in the center of Antalya. [ABSTRACT FROM AUTHOR]

Assessment of seismic vulnerability of urban areas provides fundamental information for activities of planning and management of emergencies. The main difficulty encountered when extending vulnerability evaluations to urban contexts is the definition of a framework of assessment appropriate for the specific characteristics of the site and providing reliable results with a reasonable duration of surveys and post-processing of data. The paper proposes a new procedure merging different typologies of information recognized on the territories investigated and for this reason called 'hybrid.' Knowledge of historical events influencing urban evolution and analysis of recurrent building technologies are used to evaluate the vulnerability indexes of buildings and building stocks. On the other hand, a vulnerability model is calibrated by means of experimental and numerical investigations on prototype buildings representative of the most recurrent typologies. In the final framework, the vulnerability index, calculated through simplified assessment forms, is linked to the seismic intensity expressed by the peak ground acceleration and associated with an index of damage expressing the economical loss. The procedure has been tested on the urban center of Lampedusa island (Italy) providing as the output vulnerability index maps, vulnerability curves, critical PGA maps, and estimation of the economical damage associated with different earthquake scenarios. The application of the procedure can be suitably repeated for medium-to-small urban areas, typically recurring in the Mediterranean by carrying out each time a recalibration of the vulnerability model. [ABSTRACT FROM AUTHOR]

The use of a newly developed earthquake simulator has allowed the production of catalogs lasting 100 kyr and containing more than 100,000 events of magnitudes ≥4.5. The model of the fault system upon which we applied the simulator code was obtained from the DISS 3.2.0 database, selecting all the faults that are recognized on the Calabria region, for a total of 22 fault segments. The application of our simulation algorithm provides typical features in time, space and magnitude behavior of the seismicity, which can be compared with those of the real observations. The results of the physics-based simulator algorithm were compared with those obtained by an alternative method using a slip-rate balanced technique. Finally, as an example of a possible use of synthetic catalogs, an attenuation law has been applied to all the events reported in the synthetic catalog for the production of maps showing the exceedance probability of given values of PGA on the territory under investigation. [ABSTRACT FROM AUTHOR]

Seismic hazard analysis provides an estimation of seismic hazard parameters like peak ground acceleration (PGA) or spectral acceleration (SA) for different periods. The extent of ground shaking and the hazard values at a particular region are estimated using ground-motion prediction equations (GMPEs)/attenuation equations. There are several GMPEs applicable for the region to estimate the PGA and SA values. These equations may result in higher or lower PGA and SA values than the region specific reported values, which are based on the parameters involved in the development of GMPEs. In this study, an attempt has been made to identify the best GMPEs for various parts of Peninsular India (PI) by performing an “efficacy test,” which make use of the average log likelihood value (LLH). Various intraplate earthquakes such as Coimbatore earthquake, Satpura earthquake, Anjar earthquake, Koyna earthquake, Bhadrachalam earthquake, Broach earthquake, Shimoga earthquake, Killari earthquake, Jabalpur earthquake, Pala earthquake, Kottayam earthquake, and Bhuj earthquake have been considered for the same. Macroseismic intensity maps of these earthquakes have been digitalized and European Macroseismic Scale (EMS) values at the surface have been synthesized. PGA value determined from each GMPE for known magnitude and hypocentral distances are then converted to EMS values. These calculated EMS values have been used to estimate LLH values which are further used to compute Data Support Index (DSI), rank and weights corresponding to a particular GMPE. Conventionally, LLH values are estimated for the entire distance range and GMPEs are ranked accordingly, but in this study, the LLH is calculated for the distance segments of 0-200 km and 200 km to maximum damaged distance in the region based on Isoseismal maps. If the maximum damaged distance is less than 200 km, a distance segment up to 200 km is adopted. Comparison between the rankings of the GMPEs in segments 0–200 km and 200–maximum damage distance is presented here. Segment-based GMPEs ranking shows different ranks, DSI and weights for each GMPE as compared to ranking considering entire distance. Finally, this study provides a list of GMPEs that perform best for the estimation of ground motion parameters in different parts of PI. This study shows that the GMPEs of HAHO-97, ATK-08, CAM-06, TOR-02, NDMA-10, and PEZA-11 perform better for the estimation of ground motion in most part of PI in the distance segment 0–200 km. The GMPEs of TOR-02, RAIY-07, and RAIY-07 (PI) perform best in the 200-maximum damage distance segment. [ABSTRACT FROM PUBLISHER]

This paper discusses comparison of recent observed ground motion parameters of Gorkha Nepal earthquake of April 25, 2015 ( M 7.8) with the predicted ground motion parameters using existing attenuation relation of the Himalayan region. The earthquake took about 8000 lives and destroyed thousands of buildings of poor quality, and the earthquake was felt by millions of people living in Nepal, China, India, Bangladesh, and Bhutan. The knowledge of ground parameters is very important in developing seismic code of seismic-prone regions like Himalaya for better design of buildings. The ground parameters recorded in recent earthquake event and aftershocks are compared with attenuation relations for the Himalayan region, and the predicted ground motion parameters show good correlation with the observed ground parameters. The results discussed in this paper will be of great use to civil engineers in updating existing building codes in the Himalayan and surrounding regions and also for the evaluation of seismic hazards. The results clearly show that the attenuation relation developed for the Himalayan region should only be used, and other attenuation relations based on other regions fail to provide good estimate of observed ground motion parameters. [ABSTRACT FROM AUTHOR]

Sikkim, the North-Eastern state of India, along with its neighbouring region is recognized as a part of the 'Alpine-Himalayan global seismic belt', which is one of the most seismically active areas of the world. Four significant earthquakes with a magnitude higher than Mw = 8.0 were reported in this area in earlier years of 1897, 1905, 1934, and 1950. The 2011 (M w = 6.9) Sikkim and 2015 (M w = 7.8) Gorkha Nepal earthquakes call attention to the need for a more accurate understanding of seismic characteristics in the Sikkim and their nearby region to minimize loss of life and properties due to future earthquakes and related co-seismic hazards. This study aims to estimate the Peak Ground Acceleration (PGA) having a known Probability of Exceedance (PoE) along Gangtok to Lachung and Gangtok to Tsomgo Lake; two strategic highways within Sikkim. The PGA with a known PoE is an essential input required for earthquake-triggered landslide susceptibility analysis on a regional scale as well as for the dynamic slope stability assessment of the prevailing hill slopes along the highways corridor in Sikkim. Therefore, a Probabilistic Seismic Hazard Analysis (PSHA) of the highway corridors in Sikkim is presented utilizing the updated earthquake catalogue, modified seismic sources, and next-generation attenuation relationships. The Uniform Hazard Spectra (UHS) and total hazard curves corresponding to the bedrock site conditions are generated employing 'EZ-FRISK' software. The variations of PGA having a 10% PoE in 50-years along the highways are estimated to identify the critical sections based on the ground acceleration parameter. • Areal seismic sources are defined and their seismic parameters are calculated. • Probabilistic seismic hazard analysis of the study area is done. • PGA map and UHS is computed for 97.9 years, 474.6 years and 2474.9 year return periods. [ABSTRACT FROM AUTHOR]

The objective of this paper was to develop the seismic hazard maps of Patna district considering the region-specific maximum magnitude and ground motion prediction equation (GMPEs) by worst-case deterministic and classical probabilistic approaches. Patna, located near Himalayan active seismic region has been subjected to destructive earthquakes such as 1803 and 1934 Bihar-Nepal earthquakes. Based on the past seismicity and earthquake damage distribution, linear sources and seismic events have been considered at radius of about 500 km around Patna district center. Maximum magnitude ( M) has been estimated based on the conventional approaches such as maximum observed magnitude ( M) and/or increment of 0.5, Kijko method and regional rupture characteristics. Maximum of these three is taken as maximum probable magnitude for each source. Twenty-seven ground motion prediction equations (GMPEs) are found applicable for Patna region. Of these, suitable region-specific GMPEs are selected by performing the 'efficacy test,' which makes use of log-likelihood. Maximum magnitude and selected GMPEs are used to estimate PGA and spectral acceleration at 0.2 and 1 s and mapped for worst-case deterministic approach and 2 and 10 % period of exceedance in 50 years. Furthermore, seismic hazard results are used to develop the deaggregation plot to quantify the contribution of seismic sources in terms of magnitude and distance. In this study, normalized site-specific design spectrum has been developed by dividing the hazard map into four zones based on the peak ground acceleration values. This site-specific response spectrum has been compared with recent Sikkim 2011 earthquake and Indian seismic code IS1893. [ABSTRACT FROM AUTHOR]

The Himalayan region has undergone significant development and to ensure safe and secure progress in such a seismically vulnerable region there is a need for hazard assessment. For seismic hazard assessment, it is important to assess the quality, consistency, and homogeneity of the seismicity data collected from different sources. In the present study, an improved magnitude conversion technique has been used to convert different magnitude scales to moment magnitude scale. The study area and its adjoining region have been divided into 22 seismogenic zones based upon the geology, tectonics, and seismicity including source mechanism relevant to the region. Region specific attenuation equations have been used for seismic hazard assessment. Standard procedure for PSHA has been adopted for this study and peak ground motion is estimated for 10% and 2% probability of exceedance in 50 years at the bed rock level. For the 10% and 2% probability of exceedance in 50 years, the PGA values vary from 0.06 to 0.36 g and 0.11 to 0.65 g, respectively considering varying b-value. Higher PGA values are observed in the southeast part region situated around Kaurik Fault System (KFS) and western parts of Nepal. [ABSTRACT FROM AUTHOR]

During the NERIES Project, an accelerometric database containing European digital information was developed. Besides event and station metadata, ground motion parameters, computed in a homogeneous manner, were assembled: PGA, PGV, AI, TD, CAV, HI and PSV( f,5%) (19,961 components, 2629 events, 547 stations). Merging small and moderate magnitude events produced a unique database capable of providing important information such as: (i) Correlations between several ground motion parameters follow analogous trends as in previous worldwide datasets, with slight corrections. (ii) Although PGA attenuations with distance show great uncertainties, four recent GMPEs recommended for Europe fit quite well the central 50% data interval for the distance range 10 < R < 200 km; outside these distances, they do not fit. (iii) Soil amplification ratios indicate that weak motion (low magnitudes and larger distances) shows larger amplification than strong motion (short distances and large magnitudes) as represented in UBC97 for the USA, but not in EC8 for Europe. (iv) Average spectral shapes are smaller than in the EC8. (v) Differences in amplification factors for PGA, PGV and HI for EC8 soil classes B and C, and differences in spectral shapes for these soil classes, indicate that EC8, Type 2 S-coefficient should be frequency dependent, as in UBC97. [ABSTRACT FROM AUTHOR]

Current regional ground motion prediction models (GMPMs) of areas lacking strong earthquake records employ imperfect methods or earthquake records. A new weighting method of seismology to clarify the application scope of point-source and finite-fault models is proposed in this study. According to the local small earthquake data, five regional parameters in the Sichuan area of China are inverted, and combined with other regional tectonic parameters, point-source models are established to synthesize the GMPMs of the peak ground acceleration (PGA) of Mw 5.0–7.0. Based on the finite-fault models, the PGA of Mw 6.0–8.5 of sites in four directions is synthesized, and GMPMs of major and minor axes are summed. In two-dimensional tabular form, the GMPMs between the point-source and finite-fault models consist of the weighted average between Mw 6.0 and 7.0; point-source estimation is used for PGA less than Mw 6.0, and finite-fault estimation is used for PGA larger than Mw 7.0. Finally, hybrid GMPMs of PGA with Mw 5.0–8.5 and distances within 300 km are established. Compared with the GMPMs of the postearthquake observation data and the recent edition of seismic hazard maps in Sichuan, there is a significant improvement in the areas lacking strong earthquake data. In contrast to the American logic tree weighting method, this method shows the advantage of avoiding many repeated calculations. • A weighted average method based on hybrid ground motion prediction models (GMPMs) of point and finite-fault sources is proposed. • Using microgenetic algorithm, five regional tectonic parameters are inverted from small earthquake records. • The PGA GMPMs of point and finite-fault sources expressed in two-dimensional tables are weighted in the transition range of Mw 6.0–7.0. [ABSTRACT FROM AUTHOR]

Northeast India is one of the most highly seismically active regions in the world with more than seven earthquakes on an average per year of magnitude 5.0 and above. Reliable seismic hazard assessment could provide the necessary design inputs for earthquake resistant design of structures in this region. In this study, deterministic as well as probabilistic methods have been attempted for seismic hazard assessment of Tripura and Mizoram states at bedrock level condition. An updated earthquake catalogue was collected from various national and international seismological agencies for the period from 1731 to 2011. The homogenization, declustering and data completeness analysis of events have been carried out before hazard evaluation. Seismicity parameters have been estimated using G-R relationship for each source zone. Based on the seismicity, tectonic features and fault rupture mechanism, this region was divided into six major subzones. Region specific correlations were used for magnitude conversion for homogenization of earthquake size. Ground motion equations (Atkinson and Boore ; Gupta ) were validated with the observed PGA (peak ground acceleration) values before use in the hazard evaluation. In this study, the hazard is estimated using linear sources, identified in and around the study area. Results are presented in the form of PGA using both DSHA (deterministic seismic hazard analysis) and PSHA (probabilistic seismic hazard analysis) with 2 and 10% probability of exceedance in 50 years, and spectral acceleration (T = 0. 2 s, 1.0 s) for both the states (2% probability of exceedance in 50 years). The results are important to provide inputs for planning risk reduction strategies, for developing risk acceptance criteria and financial analysis for possible damages in the study area with a comprehensive analysis and higher resolution hazard mapping. [ABSTRACT FROM AUTHOR]

Abstract: The seismic hazard value of any region depends upon three important components such as probable earthquake location, maximum earthquake magnitude and the attenuation equation. This paper presents a representative way of estimating these three important components considering region specific seismotectonic features. Rupture Based Seismic Hazard Analysis (RBSHA) given by Anbazhagan et al. (2011) is used to determine the probable future earthquake locations. This approach is verified on the earthquake data of Bhuj region. The probable earthquake location for this region is identified considering earthquake data till the year 2000. These identified locations match well with the reported locations after 2000. The further Coimbatore City is selected as the study area to develop a representative seismic hazard map using RBSHA approach and to compare with deterministic seismic hazard analysis. Probable future earthquake zones for Coimbatore are located considering the rupture phenomenon as per energy release theory discussed by Anbazhagan et al. (2011). Rupture character of the region has been established by estimating the subsurface rupture length of each source and normalized with respect to the length of the source. Average rupture length of the source with respect to its total length is found to be similar for most of the sources in the region, which is called as the rupture character of the region. Maximum magnitudes of probable zones are estimated considering seismic sources close by and regional rupture character established. Representative GMPEs for the study area have been selected by carrying out efficacy test through an average log likelihood value (LLH) as ranking estimator and considering the Isoseismal map. New seismic hazard map of Coimbatore has been developed using the above regional representative parameters of probable earthquake locations, maximum earthquake magnitude and best suitable GMPEs. The new hazard map gives acceleration values at bedrock for maximum possible earthquakes. These results are compared with deterministic seismic hazard map and recently published probabilistic seismic hazard values. [Copyright &y& Elsevier]

This article presents the latest generation of ground-motion models for the prediction of elastic response (pseudo-) spectral accelerations, as well as peak ground acceleration and velocity, derived using pan-European databases. The models present a number of novelties with respect to previous generations of models (Ambraseys et al. in Earthq Eng Struct Dyn 25:371-400, , Bull Earthq Eng 3:1-53, ; Bommer et al. in Bull Earthq Eng 1:171-203, ; Akkar and Bommer in Seismol Res Lett 81:195-206, ), namely: inclusion of a nonlinear site amplification function that is a function of $$\text{ V }_\mathrm{S30}$$ and reference peak ground acceleration on rock; extension of the magnitude range of applicability of the model down to $$\text{ M }_\mathrm{w}$$ 4; extension of the distance range of applicability out to 200 km; extension to shorter and longer periods (down to 0.01 s and up to 4 s); and consistent models for both point-source (epicentral, $$\text{ R }_\mathrm{epi}$$ , and hypocentral distance, $$\text{ R }_\mathrm{hyp}$$ ) and finite-fault (distance to the surface projection of the rupture, $$\text{ R }_\mathrm{JB}$$ ) distance metrics. In addition, data from more than 1.5 times as many earthquakes, compared to previous pan-European models, have been used, leading to regressions based on approximately twice as many records in total. The metadata of these records have been carefully compiled and reappraised in recent European projects. These improvements lead to more robust ground-motion prediction equations than have previously been published for shallow (focal depths less than 30 km) crustal earthquakes in Europe and the Middle East. We conclude with suggestions for the application of the equations to seismic hazard assessments in Europe and the Middle East within a logic-tree framework to capture epistemic uncertainty. [ABSTRACT FROM AUTHOR]

Seismically active Himachal Pradesh and adjoining regions comprising Himalayan orogenic belt with the experience of the great Kangra earthquake of 1905, has high potential for river valley projects. There are already operating hydropower projects, some under construction and a few more coming up. In view of this it is important to know the ground motion nature for various locales. The present study is about estimation of Peak Ground Acceleration (PGA) for the state of Himachal Pradesh and adjoining regions using probabilistic seismic hazard analysis (PSHA) approach. Standard procedure for PSHA has been adopted for this study and peak ground motion has been estimated for 10% and 2% probability of exceedance in 50 years at the bed rock level considering two cases: (i) varying b-value for each source zone, (ii) constant b-value for each source zone. For 10% probability of exceedance in 50 years, the PGA values vary from 0.096 to 0.15 g and 0.09 to 0.26 g considering varying b-value, and constant b-value, respectively. In case of 2% probability of exceedance in 50 years, the PGA varies between 0.07 to 0.24 g considering varying b-values and 0.14 to 0.37 g considering constant b-values. Higher PGA values are observed in the southeast part considering varying b-values whereas the region situated around Kaurik Fault System (KFS) has shown higher PGA values in case of constant b-value. [ABSTRACT FROM AUTHOR]

Parameters related to local site conditions represent an essential information for earthquake hazard evaluation and seismic risk mitigation at any region. In this research, the authors determine the local site characteristics and seismic ground motions around the Nile River, south of Cairo City, Egypt. This area suffered from a moderate earthquake (Mw 5.8) on 12 October 1992 and influenced by a soil liquefaction. Furthermore, the area is covered by soft sediments with large thickness, which may amplify seismic waves and lead to more damage in the event of earthquakes occurrence. Microtremor survey was carried out at six liquefiable sites in the study area by array of seismic stations. The recorded data was analyzed by the Centerless Circular Array (CCA) method to infer the shear wave velocity (Vs). The dispersion curves yielded from this analysis cover frequency range from 2.3 to 13.5 Hz. An inversion process was applied to get the Vs profile. The obtained velocities were averaged at 30 m depth (Vs 30) which in turn have been used for a soil classification and for calculating the bearing capacity of soil. The H/V spectral ratio method was used for an experimental estimation of the site predominant frequency and its corresponding amplitude of seismic waves. Moreover, seismic amplification was calculated using the shear wave velocities. The Peak Ground Acceleration (PGA) and seismic intensity (MMI) were calculated for the October 12, 1992, earthquake. The results reveal Vs 30 values from 170 to 240 m/s. Soil Class D is predominant in the study area. The amplification factor ranges from 2.5 to 4.5, corresponding to predominant frequency from 0.5 to 1.4 Hz. The allowable bearing capacity ranges from 0.7 to 1.0 Kg/cm2. The PGA at the surface ranges from 0.16 to 0.4 g. The calculated seismic intensity (MMI) ranges from VII to VIII which are the same with those observed during the 12 October 1992 earthquake. The parameters estimated in this research may effectively contribute to the earthquake risk reduction in the study area. • In this study we determine the local site and seismic ground motion parameters at six liquefiable sites around the Nile River, south of Cairo City, Egypt. • The employed data set composed of microtremor observations which recorded via single and multi- stations. • The recorded data was analyzed using CCA and HVSR methods. • The results reveal Vs30 (170–240 m/s), with a predominant site class D at the study area. Seismic amplification (2.5–4.5) corresponding to predominant site frequency (0.5–1.4 Hz). Allowable bearing capacity (0.7–1.0 Kg/cm2). Peak Ground Acceleration at the surface (PGAs = 0.16–0.4 g) and seismic intensity (MMI = VII-VIII) in a good consistency with the observation data of the 1992 Cairo earthquake. [ABSTRACT FROM AUTHOR]

The Himalayas are one of very active seismic regions in the world where devastating earthquakes of 1803 Bihar-Nepal, 1897 Shillong, 1905 Kangra, 1934 Bihar-Nepal, 1950 Assam and 2011 Sikkim were reported. Several researchers highlighted central seismic gap based on the stress accumulation in central part of Himalaya and the non-occurrence of earthquake between 1905 Kangra and 1934 Bihar-Nepal. The region has potential of producing great seismic event in the near future. As a result of this seismic gap, all regions which fall adjacent to the active Himalayan region are under high possible seismic hazard due to future earthquakes in the Himalayan region. In this study, the study area of the Lucknow urban centre which lies within 350 km from the central seismic gap has been considered for detailed assessment of seismic hazard. The city of Lucknow also lies close to Lucknow-Faizabad fault having a seismic gap of 350 years. Considering the possible seismic gap in the Himalayan region and also the seismic gap in Lucknow-Faizabad fault, the seismic hazard of Lucknow has been studied based on deterministic and the probabilistic seismic hazard analysis. Results obtained show that the northern and western parts of Lucknow are found to have a peak ground acceleration of 0.11-0.13 g, which is 1.6- to 2.0-fold higher than the seismic hazard compared to the other parts of Lucknow. [ABSTRACT FROM AUTHOR]

The delineation of seismic source zones plays an important role in the evaluation of seismic hazard. In most of the studies the seismic source delineation is done based on geological features. In the present study, an attempt has been made to delineate seismic source zones in the study area (south India) based on the seismicity parameters. Seismicity parameters and the maximum probable earthquake for these source zones were evaluated and were used in the hazard evaluation. The probabilistic evaluation of seismic hazard for south India was carried out using a logic tree approach. Two different types of seismic sources, linear and areal, were considered in the present study to model the seismic sources in the region more precisely. In order to properly account for the attenuation characteristics of the region, three different attenuation relations were used with different weightage factors. Seismic hazard evaluation was done for the probability of exceedance (PE) of 10% and 2% in 50 years. The spatial variation of rock level peak horizontal acceleration (PHA) and spectral acceleration (Sa) values corresponding to return periods of 475 and 2500 years for the entire study area are presented in this work. The peak ground acceleration (PGA) values at ground surface level were estimated based on different NEHRP site classes by considering local site effects. [ABSTRACT FROM AUTHOR]

This paper presents a detailed study on the seismic pattern of the state of Karnataka and also quantifies the seismic hazard for the entire state. In the present work, historical and instrumental seismicity data for Karnataka (within 300 km from Karnataka political boundary) were compiled and hazard analysis was done based on this data. Geographically, Karnataka forms a part of peninsular India which is tectonically identified as an intraplate region of Indian plate. Due to the convergent movement of the Indian plate with the Eurasian plate, movements are occurring along major intraplate faults resulting in seismic activity of the region and hence the hazard assessment of this region is very important. Apart from referring to seismotectonic atlas for identifying faults and fractures, major lineaments in the study area were also mapped using satellite data. The earthquake events reported by various national and international agencies were collected until 2009. Declustering of earthquake events was done to remove foreshocks and aftershocks. Seismic hazard analysis was done for the state of Karnataka using both deterministic and probabilistic approaches incorporating logic tree methodology. The peak ground acceleration (PGA) at rock level was evaluated for the entire state considering a grid size of 0.05° × 0.05°. The attenuation relations proposed for stable continental shield region were used in evaluating the seismic hazard with appropriate weightage factors. Response spectra at rock level for important Tier II cities and Bangalore were evaluated. The contour maps showing the spatial variation of PGA values at bedrock are presented in this work. [ABSTRACT FROM AUTHOR]

This study presents the future seismic hazard map of Coimbatore city, India, by considering rupture phenomenon. Seismotectonic map for Coimbatore has been generated using past earthquakes and seismic sources within 300 km radius around the city. The region experienced a largest earthquake of moment magnitude 6.3 in 1900. Available earthquakes are divided into two categories: one includes events having moment magnitude of 5.0 and above, i.e., damaging earthquakes in the region and the other includes the remaining, i.e., minor earthquakes. Subsurface rupture character of the region has been established by considering the damaging earthquakes and total length of seismic source. Magnitudes of each source are estimated by assuming the subsurface rupture length in terms of percentage of total length of sources and matched with reported earthquake. Estimated magnitudes match well with the reported earthquakes for a RLD of 5.2% of the total length of source. Zone of influence circles is also marked in the seismotectonic map by considering subsurface rupture length of fault associated with these earthquakes. As earthquakes relive strain energy that builds up on faults, it is assumed that all the earthquakes close to damaging earthquake have released the entire strain energy and it would take some time for the rebuilding of strain energy to cause a similar earthquake in the same location/fault. Area free from influence circles has potential for future earthquake, if there is seismogenic source and minor earthquake in the last 20 years. Based on this rupture phenomenon, eight probable locations have been identified and these locations might have the potential for the future earthquakes. Characteristic earthquake moment magnitude ( M) of 6.4 is estimated for the seismic study area considering seismic sources close to probable zones and 15% increased regional rupture character. The city is divided into several grid points at spacing of 0.01° and the peak ground acceleration (PGA) due to each probable earthquake is calculated at every grid point in city by using the regional attenuation model. The maximum of all these eight PGAs is taken for each grid point and the final PGA map is arrived. This map is compared to the PGA map developed based on the conventional deterministic seismic hazard analysis (DSHA) approach. The probable future rupture earthquakes gave less PGA than that of DSHA approach. The occurrence of any earthquake may be expected in near future in these eight zones, as these eight places have been experiencing minor earthquakes and are located in well-defined seismogenic sources. [ABSTRACT FROM AUTHOR]